9 The Adrenals and their Hormones Flashcards
Q: Where are the adrenal glands? Aka?
A: Embedded on the superior pole of each of the two kidneys
Sometimes called the suprarenal glands
Q: How many arteries and veins do the adrenal glands have? What does each one drain into?
A: many arteries but one vein (heavily perfused tissue)
left adrenal vein drains into renal vein
right adrenal veins drains into IVC-> heart
Q: Label a cross section of an adrenal gland. (6)
A: oval with a centre and 3 rings
tributary of central vein in medulla
centre= adrenal medulla
outer part of the adrenal gland is the Cortex which has 3 zones:
- Zona Glomerulosa
- Zona Fasciculata
- Zona Reticularis
capsule on outside
Q: How does the structure vary in the adrenal cortex? (2) Describe blood flow. (3)
A: Zona Fasciculata - the cells line up as strings
Zona Reticularis doesn’t really have a pattern
blood flow to the adrenal cortex is from the arteries that feed the outside of the gland
blood then heads towards tributary of central vein via 2 methods:
- most passes through cells
- some vessels which go through the cortex to get to the adrenal medulla
Q: How does hormone production vary in the adrenal glands? (2)
How does one affect the other?
A: medulla produces catecholamine hormones
cortex produces corticosteroid hormones
as corticosteroids move towards central vein, there is a positive effect on promoting noro and adrenaline production
Q: Give 3 examples of hormones produced by the medulla. Type?
A: catecholamine hormones:
- adrenaline 60% (epinephrine)
- noradrenaline 20% (norepinephrine)
- dopamine in small amounts
Q: Give 3 examples of hormones produced by the cortex. Type?
A: corticosteroid hormones:
- mineralocorticoids (aldosterone)
- glucocorticoids (cortisol)
- sex hormones (androgens, oestrogens)
Q: How do cortical cells produce hormones? (5) How do you get specific hormones?
A: corticoSTEROID hormones
- cholesterol is delivered and stored as FA esters in cell cytoplasm
- stimulus causes esterase to liberate cholesterol
- StAR protein takes cholesterol into mitochondria
- hormone is produced
- released from mito and not stored because they are lipophilic and can pass easily through the membranes
depends on the enzymes present
Q: What’s the precursor of aldosterone? What’s the precursor of oestrogens?
A: progesterone
androgens
Q: What can cholesterol become in the adrenals? (3) gonads? (3)
A: - Mineralocorticoids (C21)
- Glucocorticoids (C21)
- (Androgens)
- Progestogens (C21)
- Androgens (C19)
- Oestrogens (C18)
Q: Which enzyme is present to produce aldosterone but not present for cholesterol? (2)
A: aldosterone synthase
lacking P450c17
Q: Which enzyme is present to produce sex steroids but not present for cholesterol? (4)
A: 17,20 lyase
17 beta HSD
aromatase
P450c5
Q: What happens once corticosteroids are made? Transport? (2)
A: move straight into blood stream- are very lipid soluble and pass through bilayer
- if unbound will be taken up cells
- when bound protein= protected
Q: Compare aldosterone and cortisol transport. (3)
A: aldosterone:
- 40% unbound= BIOACTIVE
- 15% CBG bound
- 45% albumin bound
cortisol:
- 10% unbound= BIOACTIVE
- 80% CBG bound
- 10% albumin bound
cortisol is more selective for corticosteroid binding protein
Q: Why does the concentration of cortisol and aldosterone vary? Figures? Difference?
A: cortisol= diurnal- changes in day (higher in morningwhile you sleep/)
-cortisol is released in PULSES - so there will be pulsatile release on top of the circadian rhythm
8am= 140-690nmol/l 4pm= 80-330nmol/l
aldosterone- NOT controlled by the pituitary so the time of day is NOT important - but your position is important because aldosterone is involved in the control of fluid and balance
140-560pmol/l
1000fold difference (more cortisol)
Q: Which receptor does cortisol bind to? Aldosterone? Explain the situation.
A: -both bind to aldosterone receptors (MR= mineralocorticoids)
-cortisol also binds to glucocorticoid receptors (GR)
The concentration of cortisol in the blood is about 1000 times greater than that of aldosterone but cortisol isn’t constantly binding with MR because:
- The kidneys have an enzyme which converts bioactive CORTISOL to CORTISONE (inactive)
- Enzyme: 11b-hydroxysteroid dehydrogenase 2
- This enzyme constantly removes the cortisol so it doesn’t interfere with the mineralocorticoid receptors
Q: Where is aldosterone specifically made?
A: Zona Glomerulosa
Q: Explain the process of aldesterone production. (4)
A: 1. LIVER produces ANGIOTENSINOGEN (a large protein)
- Renin (released by juxta-glomerular cells= in kidneys) breaks down angiotensinogen to ANGIOTENSIN I
- Then, ACE (angiotensin converting enzyme= abundant in lungs) converts angiotensin I to ANGIOTENSIN II
- ANGIOTENSIN II stimulates the zona glomerulosa to produce aldosterone by binding to receptors
Q: What does ANGIOTENSIN II do? (2)
A: - the zona glomerulosa to produce aldosterone
-VASOCONSTRICTOR
Q: What affects aldosterone production? (4)
A: -renin
- Corticotrophin has a permissive effect - it will enhance the renin-angiotensin system
- If the blood plasma sodium ion concentration falls, it has a direct effect in stimulating aldosterone production - so there is more sodium reabsorption and sodium concentration returns to normal
- increase in potassium concentration stimulates aldosterone production leading to increased secretion of potassium
Q: What causes the secretion of renin? where? What is the effect of this?
A: low renal perfusion pressure RPP in afferent arteriole leading to glomerulus
granular cells
causes production of substances -> that lead to production of substances -> lead to constriction of efferent arteriole
=> pressure builds back up and RPP increases
Q: Aside from RPP, what causes the secretion of renin? (2)
A: renal sympathetic activity- fight/flight response increases renin production
decreased Na+ load passing through distil convoluted tubule
- Na+ moves out from surrounding cells and enters lumen
- cells shrink and cause renin production
- aldosterone will promote Na reuptake
Q: Describe the hypothalamo-pituitary-adrenocortical axis. (6) Graph?
A: stressor ->
hypothalamic hormones = CRH ->
pitutiary gland -> acts on corticotrophs (basophilic cells in the anterior pituitary)
- > ACTH production
- > affect adrenal gland
- > cortisol production
both ACTH and cortisol show diurnal rhythm (low between 8am and 8pm and small spikes as cortisol is released in pulses)
Q: Name a large stimulus for cortisol secretion. Examples? (3) Baseline?
A: stress
bacterial infection
physical trauma
exam stress
constantly produced, stressed or not
